Embroidery machines are generally controlled by programs. Often, a separate program is required for each embroidery design. Few systems previously available provide the ability to modify existing embroidery design programs, with such prior art systems, by way of example, varying the parameters associated with a stitch pattern design in order to control stitching machinery, such as is disclosed in U.S. Pat. Nos. 4,326,473; 4,821,662; 4,720,795; 4,352,334; 5,191,536; 4,807,143; 4,849,902. Some of these prior art systems are capable of scaling pattern sizes or making other modifications to existing pattern designs either input by the user or stored in memory. However, these prior art systems do not create a self-generating embroidery design pattern based on fractal geometry where the design conforms to an area defined by an outline boundary, especially one which may be an asymmetrical or irregular polygon shape.
Fractal geometry itself is well known. Examples are described in Computer Graphics: Principles and Practice, 2nd Ed., at page 1020, and in an article entitled “A Unified Approach to Fractal Curves and Plants”, by Dietrnar Saupe, at pages 273–286 of The Science of Fractal Images, Springer-Verlage, New York 1988. Our prior U.S. Pat. No. 5,430,638, entitled “Method for Creating Self-Generating Embroidery Design”, issued Jul. 4, 1995, the disclosure of which is specifically incorporated by reference herein in its entirety, discloses an efficient method for creating self-generating patterns based on fractal geometry.
However, the use of fractal geometry for self-generating patterns is limited by the ability to calculate and apply the fractal shape to an area within a given outline boundary. Asymmetrical outline boundaries defining irregular polygons, of which embroidered numbers, symbols, paisleys and letters are examples, may likely incorporate curves, corners, or other irregular features that inhibit the application of a fractal algorithm to effectively generate an appropriate fractal shape to represent certain embroidery techniques, such as a stippling stitch pattern, to be applied to that area.
Stippling stitch patterns typically follow a non-intersecting pathway that is usually curving and/or randomly displacing over a given area of an embroidery surface, which may be an embroidered article, fabric or workpiece, for instance, a quilt. Stippling stitch patterns are usually composed of run stitches and provide a raised texture to the surface. In quilting applications stippling is used as a decorative stitch to “quilt” the three layers of a quilt together (the backing, the batting, and the patched or appliquéd top layer. Stippling adds a decorative relief around the appliqué or design in each patch square and has the twin objectives of holding the three layers together as well as being a decorative stitch. The intermittent nature of the stippling and the desire that it be relatively uniformly applied over the area, contrasting raised areas separated by the stippling stitches, distinguish this type of stitching from fill stitching or border stitching, and its seemingly random nature, and curved pattern, make application of automatically generated stippling in machinery embroidered fabrics difficult.
Typically, stippling has been done first by hand manipulation of the work piece by a highly skilled artisan to create the curving visual effect, and then the resulting design is converted to a data format for storage. This may be recorded in stitch data format, or converted to an outline data format that can be further manipulated and edited on a computer display. Yet, the initial manual manipulation requires significant training and experience to arrive at a visually appealing stippling effect. For home embroidery program users this provides a potential drawback in computer based home embroidering systems in that no reliable computer generated pattern could adequately reproduce a desired stippling effect.
The interest in reproducing more complicated and irregular embroidery patterns and designs automatically, while achieving levels of quality formerly restricted to manually created patterns, points out the limitations in using automatically generated fractal shapes to prepare the stippling patterns. This is especially so where, as is usual, the desired stippling area is asymmetrical or irregular.